In related art, in an audio coding technique of moving picture experts group (MPEG) advanced audio coding (AAC) (ISO/IEC14496-3:2001), it is possible to record auxiliary information of downmixing or dinamic range compression (DRC) in a bit stream and use the auxiliary information at a reproduction side according to an environment of the reproduction side (see, for example, Non-Patent Literature 1).
Use of such auxiliary information enables an audio signal to be downmixed at the reproduction side or volume to be appropriately controlled through the DRC.